Off-center rattling and anisotropic expansion of type-I clathrates studied by Raman scattering

Y. Takasu; T. Hasegawa; N. Ogita; M. Udagawa; M. A. Avila; K. Suekuni; T. Takabatake

doi:10.1103/PhysRevLett.100.165503

Off-center rattling and anisotropic expansion of type-I clathrates studied by Raman scattering

Y. Takasu, T. Hasegawa, N. Ogita, M. Udagawa, M. A. Avila, K. Suekuni, T. Takabatake

Research output: Contribution to journal › Article › peer-review

54 Citations (Scopus)

Abstract

Dynamical motions of the guest ions in type-I clathrates Sr8Ga16Si30-xGex and Ba8Ga16Si30-xGex have been studied by Raman scattering spectroscopy, to clarify the role of guest vibration modes in these systems with unusual thermal transport behaviors. An anomalous decrease of the guest energies with decreasing temperature is observed for both systems. The Ge-doping expands the cage surrounding the 6d site anisotropically for Sr8Ga16Si30-xGex, but isotropically for Ba8Ga16Si30-xGex. Especially for Sr8Ga16Si30-xGex, off-center rattling arises simultaneously with the anisotropic expansion, and it is confirmed that these anomalies play a crucial role to suppress lattice thermal conductivity in these systems.

Original language	English
Article number	165503
Journal	Physical review letters
Volume	100
Issue number	16
DOIs	https://doi.org/10.1103/PhysRevLett.100.165503
Publication status	Published - Apr 24 2008
Externally published	Yes

All Science Journal Classification (ASJC) codes

Physics and Astronomy(all)

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10.1103/PhysRevLett.100.165503

Cite this

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title = "Off-center rattling and anisotropic expansion of type-I clathrates studied by Raman scattering",

abstract = "Dynamical motions of the guest ions in type-I clathrates Sr8Ga16Si30-xGex and Ba8Ga16Si30-xGex have been studied by Raman scattering spectroscopy, to clarify the role of guest vibration modes in these systems with unusual thermal transport behaviors. An anomalous decrease of the guest energies with decreasing temperature is observed for both systems. The Ge-doping expands the cage surrounding the 6d site anisotropically for Sr8Ga16Si30-xGex, but isotropically for Ba8Ga16Si30-xGex. Especially for Sr8Ga16Si30-xGex, off-center rattling arises simultaneously with the anisotropic expansion, and it is confirmed that these anomalies play a crucial role to suppress lattice thermal conductivity in these systems.",

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T1 - Off-center rattling and anisotropic expansion of type-I clathrates studied by Raman scattering

AU - Takasu, Y.

AU - Hasegawa, T.

AU - Ogita, N.

AU - Udagawa, M.

AU - Avila, M. A.

AU - Suekuni, K.

AU - Takabatake, T.

PY - 2008/4/24

Y1 - 2008/4/24

N2 - Dynamical motions of the guest ions in type-I clathrates Sr8Ga16Si30-xGex and Ba8Ga16Si30-xGex have been studied by Raman scattering spectroscopy, to clarify the role of guest vibration modes in these systems with unusual thermal transport behaviors. An anomalous decrease of the guest energies with decreasing temperature is observed for both systems. The Ge-doping expands the cage surrounding the 6d site anisotropically for Sr8Ga16Si30-xGex, but isotropically for Ba8Ga16Si30-xGex. Especially for Sr8Ga16Si30-xGex, off-center rattling arises simultaneously with the anisotropic expansion, and it is confirmed that these anomalies play a crucial role to suppress lattice thermal conductivity in these systems.

AB - Dynamical motions of the guest ions in type-I clathrates Sr8Ga16Si30-xGex and Ba8Ga16Si30-xGex have been studied by Raman scattering spectroscopy, to clarify the role of guest vibration modes in these systems with unusual thermal transport behaviors. An anomalous decrease of the guest energies with decreasing temperature is observed for both systems. The Ge-doping expands the cage surrounding the 6d site anisotropically for Sr8Ga16Si30-xGex, but isotropically for Ba8Ga16Si30-xGex. Especially for Sr8Ga16Si30-xGex, off-center rattling arises simultaneously with the anisotropic expansion, and it is confirmed that these anomalies play a crucial role to suppress lattice thermal conductivity in these systems.

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Off-center rattling and anisotropic expansion of type-I clathrates studied by Raman scattering

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